Transverse expansion and contraction joint



F 1943- F. ,o. HELTZEL 2,309,767

TRANSVERSE EXPANSION AND CONTRACTION JOINT Filed Dec. 10, 1940 Patented Feb. 2, 1943 TRANSVERSE EXPANSION AND CONTRACTION JOINT Francis Heltzel, Philadelphia, Pa. Application December 10, 1940, Serial No. 369,411

4 Claims.

The invention relates to joints such as are used in concrete pavement construction, and more particularly to a transverse joint designed to compensate for expansion and contraction of the pavement due to changes in temperature and moisture content.

It is common practice to form transverse joints in concrete pavements with pre-molded fillers of asphalt or similar material between sections of to transfer the load one section of concrete to another it is place transload doweling through the joints. In order to provide voids under the movement of the concrete sections to permit for expansion and contraction around the dowel pins or bars various devices have been used in the past none of which are entirely satisfactory.

It is an object of the present invention to provide doweling for a transverse joint in which a block of cork or similar compressible material is attached to the end of the dowel bar by means of a spring clip, thus, permitt'ng the cork block to be compressed as the concrete sections expand.

It is another object of the inventionto provide anexpansion and contraction joint formed of a plurality of chairs made of strap iron, wire or the like, having tie-bars welded thereto and provided with slots to receive a dowel pin or bar preferably of I-cross-sectional shape.

A further object is to provide a transverse joint of this character in which the chairs are positioned in place upon the road base or foundation by stakes or pins.

The above objects together with others which will be apparent from from customary to the drawing and following description, or which may be later referred to, may be attained by constructing the improved transverse expansion and contraction joints in the manner illustrated in the accompanying drawing in which Figure 1 is a transverse sectional view through a pre-molded joint showing the improved construction of chair, tie-bars and dowel pin;

Fig. 2, a detail fragmentary plan View of an end portion of the dowel bar showing the compressible cork block attached thereto by a spring clip;

Fig. 3, a section taken as on the line 33, Fig. 1;

Fig. 4, a section taken as on the line 4-4, Fig. 1;

Fig. 5, an elevation on a smaller scale showing a portion of a contraction joint formed with the improved device;

Fig. 6, a fragmentary longitudinal sectirn through a portion of a pavement on a smaller scale showing an expansion joint and a contraction joint;

Fig. '7, a. view similar to Fig. 1 on a smaller scale showing a modified form of the invention; and' Fig. 8, a section taken as on the line 8-8, Fig. 7.

Similar numerals refer to similar parts throughout the several views.

The improved joint to which the invention pertains includes a plurality of spaced chairs, indicated generally by the numeral Each of these chairs may be formed from a single length of strap iron, wire or the like comprising the horizontal base portion II, the upright forward leg l2, formed at the forward end of the base portion, the upright rear leg l3, formed at the rear end of the base portion, the forwardly disposed, horizontal portion 14, at the upper end of the rear leg, the upright extension 15 at the forward end of the horizontal portion I4, and the rearwardly disposed terminal flange l6 at the top of the upright extension.

Tie-rods ll connect the several chairs of each joint together, being preferably connected to each end of the horizontal base portion H, by forming the metal of the chair to fit around the tierods as at l8, and welding the tie-rods thereto as at l9; and by forming a substantially semicylindric portion 20, near the upper end of the front leg l2, and welding the upper tie-rod ll thereto, as shown at 2|.

The upper end of above the semi-cylindric portion 20, as shown at 22, and the slot is preferably reduced at its upper end, as at 23, for a purpose to be later explained. A central slot 24, aligned with the slot 22. is formed throughout the entire length of the upright extension l5, sad slot extending from the horizontal portion M to the terminal flange IS.

A pin or stake 25, provided with a head 26, is adapted to be driven down through apertures 21, 28, and 29, in the terminal flange l6, horizontal portion l4 and base portion II, respectively, and into the road foundation or base, as shown in Fig. 1 for the purpose of positioning each chair.

The premolded joint 30 may be formed of any usual and well-known asphalt or bitumen composition, as in ordinary practice and is provided with apertures or slots 3|, spaced at proper intervals to register with the slots 22 and 24 of the several chairs used in the construction of the joint.

A dowel 32, preferably of I-beam cross-sectional shape, is located through each opening 3| in the pre-molded joint 30, and through the slots 22 and 24 of the corresponding chair, the rear end of the dowel butting against the pin 25, and

the front leg I2 is slotted,

the other end of the dowel being located substantially an equal distance from the pre-molded joint 30. This latter halt of the dowel may be painted or coated as required by State specifications, and forms a slip dowel upon which the corresponding slab oi concrete may expand or contract.

For the purpose of permitting the necessary amount of expansion, a block 33, oi. cork, or other readily compressible material, is detachable connected to the outer end of the dowel 32, as by the substantially U-shape, spring clip 34, the legs 35 of which are preferably ofl-set toward each other so as to slidably fit upon the reduced web portion of the I-beam dowel, and are of sumcient width to fit between the enlarged upper and lower portions of the spring clip may slide upon danger of tilting.

In order to securely hold the cork block 33 in place while the concrete is poured, one or more blisters or indentations may be formed in the spring clip, as shown at 36.

A removable joint shield, or cap 31, of inverted channel form, may be placed upon the upper edge of the re-molded joint 30, to protect the same while the concrete is being poured, after which the shield may be removed and used again upon other joints.

In order to form an integral structure, the inner end of each dowel 32 may be are welded to the corresponding chair, at the juncture of the horizontal portion I 4 and the upright extension l5, as indicated at 38 in Fig. 1.

As shown at 2m in Fig. l, the dowel member 32 may also be welded to the upper portion of the leg l2.

Where it is desired to provide contraction joints between the expansion joints of the pavement, a metal strip 39, notched on its lower edge at spaced points as at 40, to fit over the dowels 32, may be placed in position, as shown in Fig. 5, and after the concrete has been poured this metal strip may be removed, forming a joint as shown at 4| in Fig. 6.

Referring now to Figs. 7 and 8, a slightly modified form of the invention is shown, in which the chair may be formed of a strip having the horizontal base portion Ila, and the upright front and rear legs I25 and i3a respectively, each having a notch or slot in its upper end conforming to the slot 2223, shown in Fig. 3, to receive the dowel 32.

The rear end of the dowel may be welded to the chair as shown at 38a, and the tie-rods I! may be the same as above described, and con.- nected to the chair in the same manner.

Owing to the change in the construction of the chair, the pin or stake above described is not practical for this modified form of the invention, and for this reason a pin 253, having its upper end hooked downward, as at 26a, is preferred.

The hooked upper end of this pin engages over the upper edge of the dowel and holds the entire assembly in position while the concrete is poured. Otherwise, this chair and associated parts may be the same as shown in Figs. 1 to 5, inclusive.

I claim:

1. A trans-load joint for concrete roads comprising a supporting chair of strip material having a horizontal base portion and upright legs at the ends thereof, tie-rods fixed to the lower ends of both legs and to the upper portion of one leg, said tie rods extending between a pluralthe dowel without dowel, whereby theity of similar chairs,

said last named leg having a slot at its upper end, a horizontal portion at the upper end of the other leg, an upright extension at the end of the horizontal portion, and having a slot therein, said slots being in horizontal alignment, said upright extension terminating the slot in its upper end for dividing the road into adjacent sections,

tervals, located intermediate the ends of the dowel member and abutting said first mentioned leg for dividing the road into adjacent sections, the dowel member extending into each of the adjacent sections of the road to transfer loads from one section to the other and prevent relative vertical movement thereof.

3. A trans-load joint for concrete roads comto fit around said tie-rods, said tie-rods extending between a plurality of similar chairs, said road into adjacent sections, the dowel member extending into each of the adjacent sections 01' the road to transfer loads from one section to the other and prevent relative vertical movement thereof.

4. A trans-load joint for concrete roads comprising a supporting chair of strip material having a horizontal base portion and upright legs at the ends thereof, one leg having a slot at its upper end, an inturned horizontal portion at the upper end of the other leg in horizontal alignment with said slot, a rigid, one piece dowel member located through the slot in said one leg joint forming member located intermediate the and having one end rigidly connected to the ends of the dowel member and abutting said first the road into adjainner end of the horizontal portion of the other mentioned leg for dividing leg, there being aligned apertures in the base porcent sections, the dowel member extending into tion and horizontal portion, a pin located 5 each of the adjacent sections of the road to through said apertures, tie rods fixed to said transfer loads from one section to the other and chair for attaching similar chairs at spaced inprevent relative vertical movement thereof.

tervals, the strip material of the chair being formed to fit around said tie rods, and a vertical FRANCIS 0. HELTZEL. 

